1. Field of the Invention
The present disclosure relates to a vacuum cleaner. More particularly, the present disclosure relates to a dust sensing unit for use in a vacuum cleaner, which can detect whether there is dust or dirt on a surface to be cleaned and inform a user of the detected result.
2. Description of the Related Art
Generally, in cleaning, a vacuum cleaner generates a strong suction force by using a suction motor, so that it draws in dust or dirt from a surface to be cleaned thus to clean the surface to be cleaned. Accordingly, the vacuum cleaner is very usefully in cleaning dust or dirt adhered to a surface to be cleaned, such as a carpet, a floor and the like.
When a user cleans a surface with the vacuum cleaner, she or he can easily perceive whether there is dust or dirt on the surface to be cleaned in a cleaning area contaminated or soiled with relatively large dust or relatively conspicuous dirt. However, the user can not easily perceive whether there is dust or dirt on the surface to be cleaned in a cleaning area soiled with relatively minute dust.
To addressee the problem as described above, the conventional vacuum cleaner has a dust sensing apparatus for detecting whether there is dust or dirt mounted in a suction nozzle, which draws in the dust or dirt from the surface to be cleaned in cleaning. Such a dust sensing apparatus is configured, so that it detects the dust or dirt drawn in through the suction nozzle in cleaning and informs a user of whether there is the drawn-in dust or dirt through a light-emitting lamp or the like. Accordingly, the user can perceive whether there is the dust or dirt on the surface to be cleaned or whether the dust or dirt is completely removed from the surface to be cleaned according to the operation of the light-emitting lamp in cleaning. However, since the dust sensing apparatus as described above is usually operated by a separate battery, there is a problem in that the battery should be charged with electricity or replaced with a new one if it is consumed.